Environmental and Human Health Risks of Aerosolized Silver Nanoparticles

Abstract

Silver nanoparticles (AgNPs) are gaining attention from the academic and regulatory communities, not only because of their antimicrobial effects and subsequent product applications, but also because of their potential health and environmental risks. Whereas AgNPs in the aqueous phase are under intensive study, those in the atmosphere have been largely overlooked, although it is well established that inhalation of nanoparticles is associated with adverse health effects. This review summarizes the present state of knowledge concerning airborne AgNPs to shed light on the possible environmental exposure scenarios that may accompany the production and popularization of silver nanotechnology consumer products. The current understanding of the toxicity of AgNPs points toward a potential threat via the inhalation exposure route. Nanoparticle size, chemical composition, crystal structure, surface area, and the rate of silver ion release are expected to be important variables in determining toxicity. Possible routes of aerosolization of AgNPs from the production, use, and disposal of existing consumer products are presented. It is estimated that approximately 14% of silver nanotechnology products that have been inventoried could potentially release silver particles into the air during use, whether through spraying, dry powder dispersion, or other methods. In laboratory and industrial settings, six methods of aerosolization have been used to produce airborne AgNPs: spray atomization, liquid-flame spray, thermal evaporation-condensation, chemical vaporization, dry powder dispersion, and manual handling. Fundamental uncertainties remain about the fate of AgNPs in the environment, their short- and long-term health effects, and the specific physical and chemical properties of airborne particles that are responsible for health effects. Thus, to better understand the risks associated with silver nanotechnology, it is vital to understand the conditions under which AgNPs could become airborne.

When enough is enough

“…(This is partly because the solubility of nanosilver is not fully understood, and the solubility influences the bioavailability which, in turn, influences the sensitivity of silver-resistant and silver-sensitive bacteria 17 .) Finally, we predict that the SCENIHR will underline the importance of silver speciation as this has been a general theme in many previous reviews 3,11,14,16,[18][19][20][24][25][26] .…”

“…The antibacterial properties of nanosilver are exploited in a very diverse set of products and applications including dietary supplements, personal care products, powdered colours, textile, paper, kitchenware and food storage. " And like many previous reviews and reports 3,10,14,[18][19][20][21]25,26 , the new report is likely to cite the Consumer Product Inventory maintained by the Project on Emerging Nanotechnologies 27 .…”

“…A further eight review articles in scientific journals followed in 2010 [11][12][13][14][15][16][17][18] , plus substantial reports commissioned by the Environmental Protection Agency (EPA) in the US (which ran to 221 pages) 19 and the Joint Research Centre (JRC) of the European Commission (426 pages) 20 . Two of the review articles in journals were also funded by the European Commission 14,16 .…”

“…Hence, we predict that the SCENIHR's upcoming review will consist of five main sections summarizing: the properties and uses of nanosilver; human and environmental toxicity; microbial resistance; risk assessment; and research needs 3,8,10,14,16,[18][19][20][24][25][26] . We also predict that the SCENIHR's report will say something along the following lines: "Nanosilver is reportedly one of the most widely used nanomaterials in consumer products today but the scale of production and use is unknown.…”

Rapid insight into C60 influence on biological functions of proteins

“…It has been proven that NPs may modify biological responses and interactions of cells, for example, help bigger molecules to get inside organs; they can be transported along neurons [4], trigger oxidative stress and inflammations [3,5]; and can be also responsible for genotoxicity and carcinogenesis [6]. Inhalation is one of the most probable and important exposure routes into the human body for various substances, in this number NPs [7][8][9][10][11].…”